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Investigations continue in an effort to determine the cause of the Marshall Fire in Boulder County. One potential cause may be an underground coal mine fire that crept to the surface. Some of the first coal mines in Colorado were along the Front Range. Coal mines in Marshall, Erie and Louisville produced coal used for home heating.
There are approximately 1,736 known abandoned coal mines in the State of Colorado. An inventory of coal mine fires in the state is completed every five years by the Colorado Department of Natural Resources Division of Reclamation Mining and Safety (DRMS). The latest inventory was conducted in 2018. At the time 38 coal mine fire sites were identified in the state of Colorado.
Underground coal mine fires can burn for decades.
How do coal fires start? The Smithsonian has a great explanation: “Some of the underground fires are natural occurrences. When coal, exposed at or near the surface by erosion, combines with oxygen, a chemical reaction produces heat. That process can build for years; low-grade, soft coals—crumbly and low in carbon—can spontaneously combust, at temperatures as low as 104 degrees Fahrenheit. Lightning or a brush fire can also ignite soft coal. The fires burn downward, acquiring air through fissures in rock and microscopic spaces between grains of dirt. An underground fire may smolder for years, or even decades, without showing signs on the surface. Eventually, however, in a process called subsidence, burning subterranean coal turns to ash, creating huge underground voids and causing overlying ground to crack and collapse—thus allowing more air in, which fans more fire. Much of the landscape of the American West— its mesas and escarpments—is the result of vast, ancient coal fires.”
The 2018 Colorado Mine Fire Inventory Report includes a map showing coal mine fire locations as well as a map of coal regions and abandoned mines in the state. The report has brief historical information on each mine and details and evaluates the hazards for each site.
For more information on coal and coal fires take a look at these reports from our library collection:
- Report on the status of fires at abandoned underground coal mines in Colorado 2005
- Reconnaissance study of coal fires in inactive Colorado coal mines 1989
- 1990 Summary of Coal Resources in Colorado
- Best practices in abandoned mine land reclamation [electronic resource] : the remediation of past mining activities. 2002
- Coal Mine Inspection Reports from 1884 – 1964